Gasoline composition



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GASOLINE COMPOSITION No Drawing. Filed Feb. 24, 1959, Ser. No. 794,793

4 Claims. (Cl. 44-72) This invention relates to liquid hydrocarbon fuel compositions, especially gasoline.

For many years the formation of ice in carburetors of gasoline engines was controlled when needed by adding a freezing point depressant such as isopropyl alcohol to the gasoline. While this expedient was often effective it required relatively large concentrations of the alcohol, e.g. up to 2 or 3% by volume, which was expensive and sometimes led to adverse effects such as the loss of the additive by Water leaching and the like. As a consequence entirely different anti-icing additives have been developed and are now used extensively, i.e. more complicated compounds usually characterized by the presence of both polar groups and hydrocarbon solubilizing groups.

Precisely why such compounds effectively prevent icing difficulties is not entirely understood. Generally being insoluble in water, they are not freezing point depressants so they probably do not actually prevent the formation of ice, but they nevertheless prevent or substantially reduce malfunctioning of the carburetor due to ice formation, and some of such compounds also prevent ice plugging of screens, pumps, injector mechanisms and the like.

With the Widespread use of such anti-icing compounds however, a new problem has appeared, involving a reduced degree of fuel cleanliness. In this sense fuel cleanliness is to be defined as freedom from solid contaminants, other than ice, capable of interfering with the smooth operation of an engine by collecting at critical points in the fuel system such as fuel filter screens and carburetor needle valves and jets. The offending material which has given rise to the present problem is principally rust, some of which occasionally forms in the vehicle fuel system but most of which appears to be from bulk storage and transportation equipment such as tanks and pipelines. Slight rusting of the walls of such equipment in contact with liquid hydrocarbons is practically inevitable eventually, even in the presence of corrosion inhibitors. The small amount of rust formed will ordinarily remain on the metal surfaces, or flake off in fairly large particles which rapidly settle out of the hydrocarbon liquid, and thus are no problem in regard to the properties of the hydrocarbon liquid itself. However, the new types of anti-icing agents, which as mentioned above are characterized by both polar groups. and hydrocarbon solubilizing groups, have a tendency to promote the dispersion of fine rust particles in the hydrocarbon liquid, whereby the fuel cleanliness problem arises.

It has now been discovered that this tendency of such anti-icing agents to disperse fine rust particles in hydrocarbon liquids such as gasoline can be substantially reduced or eliminated by adding to the gasoline containing the anti-icing additive a minor amount of a glycol, such as 2-methyl-2,4-pentanediol. That such glycols can reverse a dispersing tendency in the particular system of concern here is especially surprising in view of the fact that they are themselves widely used in industry as coupling agents and dispersants.

Instead of 2-methyl-2,4-pentanediol, it is of course pos States Patent sible to use related compounds such as 2-ethyl-1,3-hexanediol, 4-oxa-2,6-heptanediol, 3-thia-LS-pentanediol, 2,2- bis(hydroxymethyl)propane, 3,3-bis(hydroxymethyDpentame, and the like.

The advantages of the compositions of the invention were demonstrated in a test devised to measure the tendency of iron oxide to settle from a suspension thereof in various gasoline samples. The gasoline sample was vigorously agitated in a graduated cylinder with 1% by weight of jewelers rouge to provide an even suspension of extremely fine particles of iron oxide, and then maintained at rest. The sample was rated in accordance with the time required for a given degree of clarification, i.e. completely clear gasoline in the upper 50% of the cylinder as determined by observation and confirmed by sampling. It was found that a typical commercial gasoline, but containing no anti-icing compound, required 40 minutes settling time to the 50% level. The same gasoline additionally containing 30 parts per million by weight of Duomeen C (a mixture of mono-N-alkyl substituted 1,3-propylenediamines wherein the alkyl groups contain an average of 12 to 14 carbon atoms and are derived from coconut oil fatty acids), an efiective anti-icing agent as described in US. Patent 2,891,850, issued June 23, 1959, required minutes settling time to the 50% level. However, when to another sample of the same gasoline, containing 30 parts per million by weight of this propylenediamine anti-icing additive, was added 250 parts per million by weight of Z-methyl 2,4- pentanediol, the settling time to the 50% level was reduced to 60 minutes.

Higher concentrations of the glycol of course are useful for a still greater benefit. Generally, however, the concentration of the glycol should be less than 0.1 by volume, and preferably no more than about 500 parts per million by weight in order to avoid possible deleterious effects such as solubilization of water in the gasoline. At least 50 parts per million by weight of the glycol should be used to obtain substantial benefits in accordance with the invention and preferably at least parts per million by weight.

The concentration of the anti-icing component such as Duomeen C should be at least 5 parts per million by weight for anti-icing effectiveness and preferably at least 10 parts per million by weight. On the other hand no more than 200 parts per million by weight is usually necessary, more especially no more than 100 parts per million by weight. Additionally, to obtain the benefits of the invention, the weight ratio of the glycol to the anti-icing additive in the gasoline compositions should be at least about 2:1 or preferably at least 4:1; it is generally not necessary or desirable that this'ratio be greater than about 40:1 and preferably it should be no greater than 20: l.

The anti-icing additives of special interest in the compositions of the invention are the N-alkyl substituted alkylenediamines, especially the mono-N-alkyl substituted propylenediamines wherein the alkyl group contains from 10 to 20 carbon atoms, and wherein the propylene group is preferably a 1,3-propylene group. Such.compounds are described in the copending application Serial No. 527,164, mentioned above. Other compounds of similar nature are also suitable, for example imidazolines such as Amine 220, i.e.,

In addition to the anti-icing agent and the glycol, the gasoline compositions of the invention can also contain conventional commercial additives, for example anti-detonants such as tetraethyl lead, iron carbonyl, methylcyclopentadienyl manganese tricarbonyl, xylidene, and

, such asalkyl boronic acids, cyclic organic borates, and

lower alkyl phosphates and phosphites, oxidation inhibitors such as N,N'-disecondarybutylphenylenediamine,

N-n-butyl-p-aminophenol and 2,6ditertiarybutyl-4-methylphenol, metal deactivators such as N,Ndisalicylal-1,2- propanediamine, and corrosion inhibitors such as alkyl acid phosphate salts of mono-N-alky1 substituted alkylenediamines or alkylamines, e.g. a mixture of monoand di-octyl acid orthophosphate neutral salts of N-tallow- 1,3-propylenediamine, or the cocoamine salt of 3-methyl 2-ethylhexyl acid orthophosphate, and such as polymerized linoleic acids, substituted imidazolines, and the hydrogenated and hydrolyzed reaction product of an olefin and maleic acid anhydride.

A typical commercial gasoline in accordance with the invention is a gasoline boiling range hydrocarbon mixture containing 3 cc. tetraethyl lead per gallon, 1.0 theory of ethylene dichloride, 0.5 theory of ethylene dibromide, 0.2 gram mols of tricresyl phosphate per gram mol of the tetraethyl lead, 1 part per million by weight of dimethyl polysiloxane fluid, 0.0005 by weight of .N,N- disecondarybutylphenylenediamine, 30 parts per million by weight of mono-N-alkyl-l,3-propylenediamine wherein the alkyl group contains an average of 12 to 14 carbon atoms and is derived from coconut oil fatty acids (i.e. Duomeen C), and 500 parts per million by weight of 2-methyl-2,4-pentanediol.

The anti-icing additive and the glycol can be added to the gasoline either separately or as an additive mixture. The latter is an especially convenient expedient and the mixtures of the anti-icing additive and the glycol as such or as a concentrate in a mineral oil, especially a solvent naphtha, kerosene or gasoline, comprise an important embodiment of the invention. A typical gasoline additive composition in accordance with this aspect of the invention consists essentially of a mixture of the abovedefined Duomeen C anti-icing agent and 2-methyl-2,4- pentanediol wherein the weight ratio of the pentanediol to the Duomeen C is 8%:1. This can be added to gasoline in a total amount of the mixture of 280 parts per million by weight to provide a gasoline composition in accordance with the invention containing 30 parts per million by weight of the anti-icing agent and 250 parts per million by weight of the glycol.

A particularly surprising advantage of the compositions of the invention arises from the fact that the antiicing function of this type of anti-icing additive is not lessened by the presence of the glycol. It has been considered that such anti-icing additives may be elfective because they may act as dispersants, i.e. to coat the small particles of ice as they form thus preventing agglomeration or crystal growth which would result in plugging of filter screens and carburetor passages, e.g. around the throttle valve while the engine is idling. Such a mechanism is consistent with the occurrence of the fuel cleanliness problem in connection with their use, as discussed above, whereby fine particles of rust tend to be maintained in suspension rather than agglomerating and settling out of the gasoline during storage. Thus it would be expected that the addition of the glycol, which reduces or eliminates the tendency of the anti-icing agent to suspend rust, would also reduce the effectiveness of the anti-icing agent to prevent icing. As a matter of fact, however, the anti-icing agent has been found to be just as efiective in the presence of the glycol as in its absence.

In reaching this conclusion it was recognized that at higher concentrations than used the compositions of this invention glycols have been known to be elfective to suppress icing. Thus it cannot be assumed, just because better anti-icing results are obtained where the glycol is added, that the anti-icing agent itself remains as effective. Therefore, a large number of actual anti-icing tests were made on gasoline containing various concentrations each of, for example, Duomeen C as the anti-icing agent and 2-methyl-2,4-pentanediol as the glycol, each alone and also together. A statistical analysis of these data proved that in concentrations contemplated herein the addition of the glycol to gasoline containing the anti-icing agent does not lessen the anti-icing effectiveness of the latter in spite of the fact that the rust-suspending characteristics of the gasoline are thereby substantially suppressed. At any rate, and most importantly from a practical point of view the gasoline compositions of the invention were thus discovered to economically provide a high degree of protection against icing without the fuel cleanliness problem.

The invention claimed is:

1. A gasoline composition consisting essentially of gasoline boiling range hydrocarbons containing from about 5 to 200 parts per million by weight of a mono- N-alkyl substituted propylenediamine wherein the alkyl group contains from 10 to 20 carbon atoms and from about 50 to 500 parts per million by weight of 2-methyl-2, 4-pentanediol, the weight ratio of said pentanediol to said propylenediamine in the gasoline composition being from about 2:1 to 40:1.

2. A gasoline composition in accordance with claim 1, wherein the mono-N-alkyl substituted propylenediamine is a mixture of mono-N-alkyl substituted 1,3-propylenediamines in which the alkyl groups contain an average of from 12 to 14 carbon atoms.

3. A gasoline additive composition consisting essentially of a mono-N alkyl substituted propylenediamine wherein the alkyl group contains from 10 to 20 carbon atoms and 2-methyl-2,4-pentanediol, the weight ratio of said pentanediol to said propylenediamine in the gasoline additive composition being from about 2:1 to 40:1.

4. A gasoline additive composition in accordance with claim 3, wherein the mono-N-alkyl substituted propylenediamine is a mixture of mono-N-alkyl substituted 1,3- propylenediamines in which the alkyl groups contain an average of from 12 to 14 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 1,359,037 Deane Nov. 16, 1920 2,315,957 Hewlett Apr. 6, 1943 2,394,083 Lintz Feb. 5, 1946 2,701,754 Haworth et a1 Feb. 8, 1955 2,891,850 Cosgrove et al. June 23, 1959 OTHER REFERENCES Hexylene Glycol, Shell Chem. Corp., Technical Booklet SC50-1, copyright 1950, page 8. 

1. A GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF GASOLINE BOILING RANGE HYDROCARBONS CONTAINING FROM ABOUT 5 TO 200 PARTS PER MILLION BT WEIGHT OF A MONON-ALKYL SUBSTITUTED PROPYLENEDIAMINE WHEREIN THE ALKYL GROUP CONTAINS FROM 10 TO 20 CARBON ATOMS AND FROM ABOUT 50 TO 500 PARTS PER MILLION BY WEIGHT OF 2-METHYL-2, 4-PENTANEDIOL, THE WEIGHT RATIO OF SAID PENTANEDIOL TO SAID PROPYLENEDIAMINE IN THE GASOLINE COMPOSITION BEING FROM ABOUT 2:1 TO 40:1. 